The range of phenomena labelled as “metonymy” is so multifarious that it may seem impossible to reduce all these phenomena to a common semantic denominator. In accordance with many traditional and modern accounts in the fields of rhetoric and linguistics, this article reconstructs metonymy as a linguistic effect upon the content of a given form, based on a figure/ground effect along the contiguity relations within a given frame and generated by pragmatic processes. Thanks to these criteria, we are able to demonstrate the internal diversity as well as the fundamental unity of metonymy with respect to numerous aspects of language (innovation and conventionality, paradigmatic and syntagmatic dimension, linguistic subsystems like grammar, lexicon, etc., different levels of conceptual abstraction, concept and referent, speaker and hearer activities, principle of relevance) and to put metonymy in its right place by distinguishing it from linguistic effects based on other conceptual, especially taxonomic, relations and from other contiguity-based effects.